tailieunhanh - Báo cáo hóa học: " Research Article Unequal Weighting for Improved Positioning in GPS-Less Sensor Networks"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Unequal Weighting for Improved Positioning in GPS-Less Sensor Networks | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2008 Article ID 281635 9 pages doi 2008 281635 Research Article Unequal Weighting for Improved Positioning in GPS-Less Sensor Networks Thomas Haenselmann Marcel Busse Thomas King and Wolfgang Effelsberg Applied Computer Science IV University of Mannheim A5 6-68159 Mannheim Germany Correspondence should be addressed to Thomas Haenselmann haenselmann@ Received 17 November 2006 Revised 9 July 2007 Accepted 8 October 2007 Recommended by Richard J. Barton Positioning can be done by means of triangulation in which triples of position-aware nodes estimate a neighbor s position with the help of distances. If a larger number of nodes exist multiple position estimates can be averaged to yield a more precise mean position. Rather than applying equal weights to each position estimate we propose an unequal weighting scheme which emphasizes those summands in the averaging process that are more reliable than others. We will show that significant improvements of the overall estimate can be achieved given that additional information about the error variance of a contributing estimate is known. A major advantage of the approach is that the precision of existing positioning systems can be improved without technical modifications. Copyright 2008 Thomas Haenselmann et al. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. 1. INTRODUCTION The value of measured data in a sensor network increases significantly if each node s position is known for example to assign the measurement to a position on a map. However the knowledge of the position of several nodes can also be helpful to jointly estimate an event s position like a distant explosion a moving animal or vehicle which may not coincide with the coordinate of